Time:  12:00  13:20 
Room: 
Doherty Hall 4303

Speaker: 
Fritz Obermeyer Department of Mathematical Sciences Carnegie Mellon University 
Title: 
Lattices of Lambda Theories

Abstract: 
Consider lambda calculus as an equational theory. We start with betaequality, and maybe also etaequality, and then add additional [sets of] equations to form congruences. The set of congruences is closed under finite intersection and arbitrary union: it is a complete lattice. The lattice of lambda theories is a wellstudied structure. I will survey some known results regarding the lattice, and discuss some lattices of theories of extensions of lambdacalculus. References: "Applying universal algebra to lambda calculus" by G Manzontetto and A. Salibra. 